I am not a plumber, but your rust seems to be pipe sweat. That metal should be thick, and gravity should do the rest. If you can hit it with a hammer and it doesn’t break the metal/junctions shouldn’t be a problem… Waiting for a plumber to tell me wrong.

I know for cast iron, my plumber used a special chain cutter. I needed a laundry connection and he cut my stack to tie in. A ratchet handle tightened the chain until the pipe broke. Made a very clean cut.

Hate to say it, but you really need a plumber to cut out that old stack. I do some plumbing but there's no way was I going to tackle cutting into my cast iron stack.

There are PLENTY of ways a do-it-yourselfer can save money...one of those ways is recognizing when you need expert assistance.

Looking at your photos, though, it doesn't look like the rust originates on the pipes you're showing us. I see that there's quite a bit of rot at the bottom, so there IS enough liquid, long-term, that needs addressing, but I also see rust on the upper section.

It would be an adventuresome project. I would do it. In addition to my own experience I learned a lot from an old retired plumber on a Q&A site. I think he is gone, old age/death. You can rent the chain cutter, mostly the best way. Sawsalls are very slow. If you are going from the bad section all the way to the roof, maybe all you need is a sledge hammer. The leaking section looks like painted cast to to me.

To undo the joints, pound a screwdriver through the poured lead and pry it out. The connector is a "Y" likely meant as a cleanout, a good idea, perhaps code. For connecting cast to PVC, you use I think it is a Fermco or such connecter. They are a rubber band. They fit the cast pipe, not the belled joints.

I am a plumber. If you do not know what you are doing you are better off to contact a plumber for an estimate on this job. Your ignorance of the most basic information such as the composition of this pipe will cause you to create more problems than this is worth. This is not a complicated job but one that requires the tools and knowledge of some very basic principles.
The weight of this pipe alone should preclude you from attempting this project.
If you don't have access to a cast iron cutter/snapper you will only ruin any sawz-all blade you attempt to cut this with. It can be replaced with simple PVC pipe so the cost of materials should not be a major factor.
Trust me. While it is satisfying to do your own work, if you don't have someone to show you how to do this, hire someone that knows what this involves.

I am a plumber. If you do not know what you are doing you are better off to contact a plumber for an estimate on this job. Your ignorance of the most basic information such as the composition of this pipe will cause you to create more problems than this is worth. This is not a complicated job but one that requires the tools and knowledge of some very basic principles.
The weight of this pipe alone should preclude you from attempting this project.
If you don't have access to a cast iron cutter/snapper you will only ruin any sawz-all blade you attempt to cut this with. It can be replaced with simple PVC pipe so the cost of materials should not be a major factor.
Trust me. While it is satisfying to do your own work, if you don't have someone to show you how to do this, hire someone that knows what this involves.

I replace a lot of cast iron pipe in my building. And I agree with Topaz on this one. It can turn into a pandora's box very easy. There are too many pit fall to list here just looking at the pictures youo have posted. You lneed experienced eyes on the job.

Looks like cast iron painted silver to me, not galvantized. Galvanived would be threaded and those are clearly cast iron hubs. I've replaced lots of rotten cast iron, and it seems the vents are worse than the drains about rotting and cracking. I'd replace it with PVC The last picture shows the hub right above the floor plate. If you can't get down further than that I'd suggest drilling out the lead and oaken and use a Ty-Seal gasket to transition to PVC. That wye is just for a cleanout and you could use a PVC test tee for the same purpose.

I've replaced piping into a cast iron pipe; just hammer and chisel until the upper part came out. Fortunately it came out without cracking the "bowl" of the cast iron receptacle it was seated into. Really, I would call a plumber unless you are prepared to pay even more if you preak any of the cast iron in the process of replacing it.

Then you seat the ABS pipe into the bowl, and pack around it with a burlap-soaked-in-cement-dust that you wet, to seal the gap. What you do for the top, I don't know. Probably that rubber sleeve with the screw clamps to connect the pipe to the pipe above - although how that works with the divergent pipe outside diameters, I don't know.

When the plumbers replaced my stack (part of a complete bathroom replumbing from underneath in the basement) they had the advantage that it went from, IIRC, 4-inch to 3-inch when it went throught the wall to vent in on the roof, but it was still cast iron above.

Then you seat the ABS pipe into the bowl, and pack around it with a burlap-soaked-in-cement-dust that you wet, to seal the gap. What you do for the top, I don't know. Probably that rubber sleeve with the screw clamps to connect the pipe to the pipe above - although how that works with the divergent pipe outside diameters, I don't know.

When I replaced the galvanized drain that lead to my stack with plastic, I asked the plumbing supply store how to mate the plastic to cast iron. They sold me a bag of oakum (like a tar impregnated strands of fiber like hemp) and some lead wool (just like steel wool, only made out of lead)
They told me to take a small piece of hardwood (oak), and stuff the joint with oakum and hammer it in place. Lather rinse repeat until the joint is about 1/2-2/3 full. Follow with the lead wool. Stuff it in and hammer away until the joint is full. Takes about 20 minutes to do the joint, and when done it looks like you used melted lead on the joint.

I've done this several times, but always working under the supervision of my brother, who is a Master Plumber. I could suggest a middle ground - work with a Plumber who would be willing to look carefully at the entire job and tell you what to cut out and where (so, for instance, there is enough cast iron left to connect a Fernco) and where you need to put in straps to support the remaining cast iron. This stuff is insanely heavy. If you are in good physical shape, and rent the chain cutter (a wonderfully fun tool that cracks the cast iron with a loud, satisfying BOOM), many plumbers would be happy to have somebody else do the (literal) "shit work", then they come in and do the non-backbreaking job of plumbing in the PVC. That's the part that requires some skill.

If you find someone willing to do this, remember to cut the cast iron in 2' sections to be able to handle it. It's that heavy.

It is one of the things you learn as a plumber, along with "Water flows downhill" and "Don't bite your nails" (the latter is especially important in a profession where one is required to get a hepatitis vaccination due to potential exposure to feces).

Any plumber who has been doing this work long enough to feel comfortable doing a main drain replacement is pretty damn beat up already and is not looking forward to lifting out the piece under your kitchen sink where the drain, stack and vent all come together. That bastard probably weighs 75 pounds.

I'd go back to looking for the real source of those rust stains. They look more like the results of leaks at the connections to sinks, toilets, tubs, etc., that have dripped down. The silver pipes were probably painted to cover that up. Cast iron lasts a really long time and does not rust out easily. A bad joint can be repaired.

Iron stacks are just the kind of thing you want a plumber for, although replacement with plastic is pretty easy, the biggest problems may come from connecting back to all those fixtures, not replacing the main pipes. And if you screw up, the result may be sewage all over the place, including inside walls and between floors.

So, knowing that I'm about to ask a very broad question, what kind of ballpark are we talking here, price-wise?

And when you replace the main stack, does that mean the entire run straight from the basement to the top floor? Does one typically need to open walls to do this? How destructive is it to the rest of the house?

I know for cast iron, my plumber used a special chain cutter. I needed a laundry connection and he cut my stack to tie in. A ratchet handle tightened the chain until the pipe broke. Made a very clean cut.

Hate to say it, but you really need a plumber to cut out that old stack. I do some plumbing but there's no way was I going to tackle cutting into my cast iron stack.

I cut mine off using a Sawzall. Cut through it like butter (OK, a lot faster then I thought it would go). It wasn't a problem at all. I used that versus a chain because it was in a tight location. It was also a lot cheaper than renting the chain cutter. I replaced a horizontal piece of pipe that connected to the vertical stack. The connection was between the new PVC and the old pipe using a rubber connector.

As to the op. surface rust is normal. Put some rust conversion stuff on it and paint it. If it's truly cracked and leaking then that needs to be addressed. In my case I made the mistake of using drain cleaner and it ate a 2" by 8" hole in the pipe. I was able to plug it up temporarily with about 3 sticks of plumbers epoxy. Since it was a horizontal leak I wasn't going to rely on that but the patch held solid for months until I cut out the pipe (fyi).

I cut mine off using a Sawzall. Cut through it like butter (OK, a lot faster then I thought it would go). It wasn't a problem at all. I used that versus a chain because it was in a tight location. It was also a lot cheaper than renting the chain cutter.

Did you have a diamond blade? Because normal metal blades wear out nearly instantly on cast iron.

I'll admit that it was sometimes a bit painful getting the end of the chain cutter behind the pipe, but that's what the Sawzall is for - to cut the wood. I've done this for all 4 of my brother's rental properties, and a number of other houses, and can't imagine chopping 30' of 4", fossilized shit filled, cast iron pipe into 2' sections with a Sawzall. And of course cutting the pipe with a saw generates dust the chain cutter doesn't (see the bit above about the crunchy center of an old sewer pipe).

When we re-plumbed each of these four houses, it was part of a gut rehab. We tore out the kitchen and the bathroom and replaced everything in the wet wall. We put a washer and dryer upstairs, so we needed drainage for that, as well as new plumbing to handle the water needs. The only cast iron that remains is in the stack going through the roof - it only carries smell and gas, so it was in fine shape, and we saw no need to disturb the roof. We had to use Plumber's Strap to support the remaining cast iron, and started cutting from the top down.

As TriPolar pointed out:

Quote:

...the biggest problems may come from connecting back to all those fixtures, not replacing the main pipes.

Absolutely! It makes no sense at all to replace the cast iron stack and not replace everything else. The only way to connect cast iron to PVC is with a Fernco, and as useful as they are, you don't want any more of them than absolutely necessary - ideally one at the bottom of the stack were the PVC joins the house sewer, and one at the top where the PVC joins the vent. And make sure the Fernco at the bottom is a metal-jacketed one. NOT a place to cheap out.

My motto is "In any given system, failure usually occurs at connection points." You do not want to have more than the absolute minimum number of connections between different types of plumbing.

Looking at the pictures again, you cannot just replace the cast iron in the wall that has been opened. You have a Y at the bottom, and as Dag Otto correctly pointed out, a useless clean-out. If you cut above the Y and attach a Fernco, you still have the useless clean-out. But there is not enough pipe below the Y to attach anything. And you cannot chisel out the lead and oakum at the top of the Y and put in PVC - again, the only acceptable connection between cast iron and PVC is a Fernco.

You could, in theory, strap the upper T in place with plumber's strap (mandatory - there is a lot of weight involved and you have to keep it from moving) cut the silver painted pipe, work the joint off, and put a Fernco to connect to the new PVC. But I wouldn't. I'd cut open the ceiling and put a new floor flange for the toilet. You're going to have to re-seat the toilet after fiddling with the cast iron and it is going to break the wax seal.

Any work you do risks causing additional damage, and - again, if this were my house - I'd remove every bit of cast iron possible, going all the way down to the concrete in the basement. The PVC costs nothing compared to the cost of patching the walls. You want to do that once, and only once.

Did you have a diamond blade? Because normal metal blades wear out nearly instantly on cast iron.

Yes, I think I used the Torch blade that was made to cut that type of material. I wouldn't cut them in 2 ft sections as it's not that heavy but I'd have to weigh the number of cuts via sawzall versus a rented chain cutter. I thought I was in for a real battle but it cut right through it. I only had to make 3 cuts and only one of them was the size we're discussion.

Quote:

Originally Posted by gaffa

I'll admit that it was sometimes a bit painful getting the end of the chain cutter behind the pipe, but that's what the Sawzall is for - to cut the wood. I've done this for all 4 of my brother's rental properties, and a number of other houses, and can't imagine chopping 30' of 4", fossilized shit filled, cast iron pipe into 2' sections with a Sawzall. And of course cutting the pipe with a saw generates dust the chain cutter doesn't (see the bit above about the crunchy center of an old sewer pipe).

The sawzall blade is half the cost of the chain cutter so depending how many cuts is necessary that would be the deciding factor.

Interesting how threads like this go on for 2 dozen posts with never a peep out of the OP. I does look like smoke is checking out our posts.

Connecting PVC to belled cast is a problem I have never needed an answer to. My bet is that somebody does have an answer. Hermann, md2000, and Rick all 3 seem to have different solutions. Might want to use schedule 40 to connect and not the lighter DWV.

I always put more weight on the posts claiming to have done it than the ones saying it can't be done. Same with the Sawsall.

And you cannot chisel out the lead and oakum at the top of the Y and put in PVC - again, the only acceptable connection between cast iron and PVC is a Fernco.

Hate to disagree, but you most certainly can dig out the lead and oakem and replace the old cast iron with a schedule 40 test tee. Just go get a 4" Ty-Seal gasket and lubricant. I've done this many times and it works like a charm. I'm curious as to why you say it can't be done.

Hate to disagree, but you most certainly can dig out the lead and oakem and replace the old cast iron with a schedule 40 test tee. Just go get a 4" Ty-Seal gasket and lubricant. I've done this many times and it works like a charm. I'm curious as to why you say it can't be done.

I stand corrected. I've never run across those before, and have never used one.

Hate to disagree, but you most certainly can dig out the lead and oakem and replace the old cast iron with a schedule 40 test tee. Just go get a 4" Ty-Seal gasket and lubricant. I've done this many times and it works like a charm. I'm curious as to why you say it can't be done.

Out of curiosity, how is this done? I was thinking of replacing the actual pipe with more cast iron but when I put a chisel to the leaded material it appeared to be a substantial amount of work. I quickly abandon this for the rubber seal connector.

Also, as it applies to the op's project, if the entire stack isn't removed is it possible to work in a PVC pipe without a rubber gasket?

Before chiseling on the lead, get a 1/4 inch drill bit and drill a bunch of holes into it. If your bit is too short it might get into a bind between the hub and the pipe and break, so have extra bits handy...the longer the better. After the holes are drilled you can dig it out with a long skinny flat-tipped screwdriver. There is a groove just inside the hub, so be sure to dig the lead out of that out, too. That's the groove the rubber gasket needs to seat in in order to work right. The bad news is that you'll need to get rid of the pipe above the hub...leave a piece about a foot long that you can grab hold of and wiggle around in circles to flatten any leftover lead. Personally, I'd just take a hammer and break it offabove the cleanout wye. The fitting end that goes into the hub isn't flat, but has a small knobby end that holds the oakem when you pack it, so be sure to dig the old oakem out. The only way I know of to connect PVC back into the hub without using the gasket is to use lead wool. The problem with this is that you'd need to get some oakem, also, and a lead packing iron. Believe me, the Ty-Seal gasket is the easiest way to go. Any plumbing supply house should have it. I've been a licensed plumber since 1985 and there's no way I'd have cast iron in my house.

Last edited by hermann; 07-14-2011 at 07:05 PM..
Reason: Spelling and to clarify

Oh, I also read above where somebody noted that the cleanout wye you have now is useless. True, but with the pipe being painted I'm led to believe that at one time the pipe was exposed and not enclosed in a wall. Doesn't make any sense to paint a pipe that's going to be in a wall.